February Rain Fills SF Drainage System

Sioux Falls didn't get snow; instead an inch and a half of rain fell on the city and that record rainfall tested out the city drainage system.

Sioux Falls has 60 different detention ponds around the city to funnel water away from streets and homes.

With the rain in the last few days, those ponds have done their job, but the big job for city workers is to make sure the inlets and outlets don't get clogged and cause problems.

"Conditions like this, we'll make sure our guys get out while it's raining, checking for that ice and checking for that snow blocking drainage up," Sioux Falls drainage engineer Andy Berg said.

Crews are unclogging the drainage ponds because if they don't, all the water would flood city streets and neighborhoods.

"We want to keep them protecting the homes, protecting the businesses and also cleaning up the water and not sending it downstream any faster than we can," Berg said.

Even though Sioux Falls has had an inch and a half of rain fall at one time before, this storm was unique because the ground was still frozen so the rain didn't soak in as much. That's why the city has been paying close attention.

"These ponds are designed to grab that water and an inch and a half with frozen ground, it filled up pretty fast. It fills up and then it's got a regulated release on it so it will release it over the next couple of days and then get back down to that low-water condition," Berg said.

And then the ponds will be ready to fill back up when the next storm hits.

Officials say as the city grows, they continue to evaluate the city drainage system and whether to add, or expand, the ponds to make sure heavy rainfalls do not cause street flooding or flooding around homes.